The book you are looking for is most likely published by Hatier . This legendary guide is considered the "gold standard" for French verb conjugation, covering nearly every verb in the French language through a system of model patterns.
If you are searching for a digital version for study purposes, these platforms often host copies: Le Nouveau Bescherelle - L'Art de Conjuguer 8000 Verbes livre de conjugaison 8000 verbes pdf exclusive
~~29,90 €~~ → 14,95 € (50% de réduction exclusivité web) "Le Nouveau Bescherelle : L'Art de Conjuguer –
Free sites often contain errors for rare verbs. This PDF was compiled by a team of three PhD linguists over 18 months, cross-referencing the Académie Française database, Le Trésor de la Langue Française, and the Bescherelle 12,000. Commercial : « Téléchargez maintenant la version PDF
If you are a student, log into Cairn.info or Scholars Portal . Many academic libraries purchase licenses for exclusive PDFs that students can download for free.